is there any way to get the Instance from a Field?
Here's a sample code:
public class Apple { // ... a bunch of stuffs.. } public class Person { @MyAnnotation(value=123) private Apple apple; } public class AppleList { public add(Apple apple) { //... } } public class Main { public static void main(String args[]) { Person person = new Person(); Field field = person.getClass().getDeclaredField("apple"); // Do some random stuffs with the annotation ... AppleList appleList = new AppleList(); // Now I want to add the "apple" instance into appleList, which I think // that is inside of field. appleList.add( .. . // how do I add it here? is it possible? // I can't do .. .add( field ); // nor .add( (Apple) field ); } } I need to use Reflection, because I'm using it with annotations. This is just a "sample", the method AppleList.add(Apple apple) is actually called by getting the method from the class, and then invoking it.
and doing so, like: method.invoke( appleList, field );
causes: java.lang.IllegalArgumentException: argument type mismatch
*EDIT* This might be helpful for someone who's looking for the same thing.
if the class Person, had 2 or more Apple variables:
public class Person { private Apple appleOne; private Apple appleTwo; private Apple appleThree; } when I get the Field, like:
Person person = new Person(); // populate person Field field = person.getClass().getDeclaredField("appleTwo"); // and now I'm getting the instance... Apple apple = (Apple) field.get( person ); // this will actually get me the instance "appleTwo" // because of the field itself... at the beginning, by looking at the line alone: (Apple) field.get( person );
made me think that it would go and get an Instance which matches Apple class.
that's why I wondered: "which Apple will it return?"
